Design Complexity: Use 3D printing for intricate shapes, CNC for precise functional parts, or vacuum casting for aesthetic prototypes.
Material Requirements: Select CNC or sheet metal for metals, 3D printing or vacuum casting for plastics, and injection molding for production-like materials.
Volume: 3D printing or CNC for one-offs, vacuum casting for small batches, rapid tooling for medium runs.
Budget and Time: 3D printing and CNC offer fast turnaround; injection molding requires more investment but suits larger batches.
Testing Needs: Choose methods that match final production materials for functional testing (e.g., CNC or injection molding).